data(heating)(1) gas central, (2) gas room, (3) electric central, (4) electric room, (5) heat pump.
For these data, the costs were calculated as the amount the system would cost if it were installed in the house, given the characteristics of the house (such as size), the price of gas and electricity in the house location, and the weather conditions in the area (which determine the necessary capacity of the system and the amount it will be run.) These cost are conditional on the house having central air-conditioning. (That is why the installation cost of gas central is lower than that for gas room: the central system can use the air-conditioning products that have been installed.)